The invention relates to a sensor placed on the skin, which can be used for metering the pulse of humans, for instance.
Sensors attached to the skin, for instance are used in pulsometers. The operation is based on the feature of the sensor comprising a contact layer whose electric conductivity varies under the pressure exerted on it. In this manner, this layer emits a signal corresponding to the pulse. The sensor is often connected to a strip, which can be tightened around the chest. A separate sensor can also be attached to the skin by means of tape or elastic bands. Separate sticker tapes can also be used for fastening the sensor.
Strips, tapes, bands, sticker tapes and similar are often unpleasant in use, because they tend to give a sensation of pressure and to harm metering or other movements in general. In many cases, there are problems in keeping the sensor in position. Thus, for instance, to keep a band in place in hard physical exercise, separate tops and similar garments have to be worn on top of the strip in order to achieve adequate and reliable contact between the sensor and the skin.
The contact layer should be brought into tight contact with the skin for the measurements to be sufficiently reliable. To ensure skin contact, liquids such as water or grease can be used between the contact layer and the skin. After the measurement, the sensor and the skin often need to be cleaned separately to avoid any hygienic inconveniences caused by the use of a sensor.